Objective: The aim of the study was to evaluate whether the visual analysis of muscle magnetic resonance imaging scans can identify specific patterns of muscle involvement.
Methods: We assessed scans from 83 patients with muscle disorders characterized by rigidity of the spine secondary to mutations in 4 different genes. The conditions studied were rigid spine syndrome (SEPN1 defects), Bethlem myopathy, and Ullrich congenital muscular dystrophy, allelic disorders caused by Col6A1, Col6A2, and Col6A3 mutations, the autosomal dominant form of Emery-Dreifuss muscular dystrophy (LMNA defects) and calpain-deficient limb girdle muscular dystrophy (CAPN3 defects). The scans of 25 patients affected by other myopathies were also reviewed as a control group. The scans were compared with the previously described patterns.
Results: In 82% of the scans in the study group (68/83) the patterns were classified as "typical" of 1 of the 5 forms studied, and in 7 (8%) were consistent with 1 of the reported patterns but not entirely typical. With one exception, the patterns identified were always consistent with the appropriate genetic diagnosis. The remaining scans (9%) had only minimal changes and were uninformative. None of the scans of the 25 patients in the control group had patterns that could be classified as typical of the 5 forms examined. The sensitivity to detect selective patterns in relation to the genetic diagnosis was 0.9.
Interpretation: These findings suggest that muscle magnetic resonance imaging could be used in clinical practice as an additional tool in the differential diagnosis of muscle disorders with prominent spinal rigidity.